Snooty Cat Waterer

A device for watering cats who will only drink fresh from the tap water. The goal here was to NOT use a micro and keep it simple.

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Roger (cat) insists on drinking from the faucet. This leads to him being thirsty a lot and the faucet getting left on more often than I would like to admit.
As a quick weekend build here were the requirements of the project
• No micro - Keep it simple
• Cannot affect useability of bath/shower

After considering several options the combination of complexity and vulnerability to water/soap scum lead me to capacitive sensing the Cat.  For this I eventually settled on using Microchip's MTCH101 capacitive proximity part for detection. This provides a standalone detection to an alleged range of 6" and is dirt cheap ($0.44 at onsies). This part has an active low output and requires only  a resistive divider to adjust the sensitivity.

 12V solenoid valve (McMaster 7877K55) intended to hook up to the toilet's fresh water feed. The system consists of two boards which were etched using the sharpie resist method.

  • 1 × MTCH101 Sensors / Proximity
  • 1 × NTGS3446T1G N-MOSFET 20V 2.5A
  • 1 × LM317 Power Management ICs / Linear Voltage Regulators and LDOs

  • First Attempt

    Brian04/02/2014 at 19:14 1 comment

    Considering how hastily built the PCB was I am pleased with how it functions. I am currently getting about 3"  range on detecting the Cat. It is a bit better for humans. Brain fart on the active low output vs N-FET. I was able to easily deadbug a P-FET on the sensor board to invert the signal to the power mosfet on the other board. Will get a schematic posted soon..

    Current issues:
    • Not been able to identify a good fitting to connect the valve to the toilet water. Currently using gravity to get water out of the tank, which does not provide adequate flow for cat's fancy.
    • Cat is adverse to new technologies.
    • Could use a one shot for keeping the valve on through sensor hiccups.

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OneShot Willie wrote 04/03/2014 at 01:46 point
Hmmm.. have you thought about just getting Roger drunk, and having an RFID chip put in? He probably won't notice after the hangover clears and probably won't even blame you for it if he does find it! Or, if he's really uptight and doesn't drink, you could hide the RFID device in his collar...

That way you could just use an RFID reader so he doesn't have to share the water with his humans or "those other pets" something simliar to this...

  Are you sure? yes | no

Brian wrote 04/03/2014 at 02:58 point
Roger is chipped, and I considered the feasibility of reading his tag. My understanding of the subdermal RFID chips is that they only have a couple mm range due to their short antennas. Also I was trying to keep this quick and cheap. All other parts besides the cap sense chip and valve were sourced from my junk bins

  Are you sure? yes | no

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